From an aerodynamic aspect, wind turbine rotor blades with thin trailing edges, that is with pressure and suction sides which converge at a point as viewed in profile, are optimal. For structural reasons, however, in particular in the case of wind turbines with a horizontal axis, very large relative profile thicknesses are required in the region of small radii, that is close to a rotor axis. In particular, a sufficient bending stiffness to ensure adequate strength of the rotor blades is attained only with large profile thicknesses. In order that flow separation does not occur in the case of large relative profile thicknesses, so-called thick profile trailing edges are used. These are used in particular in the region of small radii in virtually all modern wind turbines.
At larger radii, that is at a greater distance from the rotor axis, thick profile trailing edges can generally no longer be used successfully because two negative effects arise owing to the higher flow speeds there. Firstly, the air is forced by the thick profile trailing edge to form, downstream of the profile, a Kármán vortex street which oscillates with a characteristic frequency, thus generating so-called trailing edge noise. The sound pressure of said noise increases with the thickness of the profile trailing edge. Secondly, owing to flow separation at the pressure-side and suction-side ends of the trailing edge, a recirculation field in which merely ambient pressure prevails is formed behind the profile trailing edge. This generates suction counter to the flow direction, which leads to an increased pressure resistance of the wind turbine rotor blade. The aerodynamic performance of the rotor blade is impaired as a result.
United States patent application publication 2010/0047070 discloses a wind turbine rotor blade in which an additional sharp-edged profile or a plate with a cross section which is constant in the longitudinal direction of the rotor blade is arranged on a thick profile trailing edge. The sharp-edged profile is intended to reduce the effective thickness of the profile trailing edge to approximately zero. In the variant with a plate, the plate is supposed to be inserted between the lower and upper half-shells of the rotor blade. It is thereby sought to counteract the vortex shedding of the flows on the pressure and suction sides.
United States patent application publication 2007/0077150 discloses a wind turbine rotor blade in which a row of bristles is arranged on a thin profile trailing edge. The bristles are intended to compensate pressure fluctuations on the two sides of the profile, and thereby counteract the generation of noise. A similar arrangement of bristles on a thin profile trailing edge on a wind turbine rotor blade is also presented by document DE 10 2008 003 188 A1.